Drier kiln



' Feb. 9', 1926.

H. R. STRAIGHT DRIER KILN 7, 1924 2 Sheets-Sheet l Filed Feb.

Feb. 9 1926.

H. R. STRAIGHT DRIER KILN Filed Feb. '7, 1924 2 Sheets-Sheet 2 jawnzbrm. 4mm-immuni QW laag Patented Feb. 9, 1.926.

- "UNITED STATES- HAL'vn n, STRAIGHT, or ADEL, Iowa.

prima. zum".

Application niearebniary 7, 11m. serial No'. 691,198;

To all whom it may concern:

Be it known that I, HALVER IL STRAIQHT, a citizen of the United States,and a resi dent of Adel, in the county of Dallas, State of Iowa, haveinventeda certain new and useful Drier Kiln, of which the following is aspecification.

This invention relates to improvements 1n drier kilns. l

The object of my invention is to provide a kiln of simple, durable andinexpensive construction, soconstructed and arranged that plastic waremay be passed through it in a continuous manner so that the ware will bedried very rapidly without checking or warping.

More specifically it is the object of my invention to provide a drierkiln so constructed and arranged that the kiln may be divided into aseries of compartments in such a manner that air may be moved throughthe ware in reverse directions as it travels from y one compartment toanother; and further so arranged that the air will travel at diii'erentvelocities as it passes through the ware in the diderent compartments.

Another object is to so construct and arrange the kiln that the pure airmay be taken into the kiln at normal temperature and passed through thekiln for drying the ware, and to introduce to the kiln quantities ofheated air such as the products cf combustion from the furnaces of theburning kilns, in such a manner that the heat from the said products ofcombustion may be radiated to the drier for the purpose of heating thecirculating air andv the ware, means being provided for introducing theproducts of combustion at a pointsome distance from the air intake endof the drier so that the ware may be cooled as it leaves the drier andthe heat from the ware utilized in heating the ware near the center ofthe drier.

I have found by actual tests and observation that plastic shale' andclay, such as used to make brick and hollow building blocks, has thecharacteristic of shrinking quite rapidly as the first part of themoisture is being taken from the ware. After carefully plotting a curveon a percentage basis, I nd that when about tive percent of the freemoisture has been taken from i the ware, the shrinkage amounts to abouttwentypercent; when` fifteen percent of the moisture has been taken, theshrinkage amounts to about forty percent; when thirt percent of themoisture has been remove the shrinkage is about sixty percent; and whenseventy percent of the moisture has been removed, the shrinkage' isabout one hundred percent.

Thus it will be seen that it is very ressential that at the beginning ofthe ,drying of the ware, the temperature, humidity and velocity of thedrying medium, whic is usually heated air, be accurately regulated, dueto the fact that the shrinkage 1s so much greater for a given percent ofmoisture removed in the beginning than4 at the latter part of theprocess.

It will further be seen that after the total shrinkage has taken place,the ware might be dried very rapidly without in'ury. I find that thebest way to accomplish the desired results is to provide a means wherebythe ware may be advanced throughout the kiln, and then to supply heatedainl at the delivery end of the kiln in quantities at a uniformvelocity. I have -best accomplished these results by the followingarrangement.

Referring to the accompanying drawings, Figure 1 is a verticallongitudinal sectional view through the intake end of my improved drierkiln. y

Figure'2 is a vertical longitudinal Sectional view of the delivery endof my improved kiln, the kiln being broken in two for the purpose ofenlarging the views. The left hand end of Figure 2 is designed to jointhe right hand end of Figure 1.-

Figure 3 is a transverse sectional view on the line 3-3 of Figure 1.

Figure 4 is a plan view of the moisture supply pan.

Figures 5 and 6 are longitudinal sectional views taken through a modiedform of my drier; and

Figure 7 is a transverse sectional view taken on the line 7--7 of Figure5.

ed upon which the ware is designed to rest so that air freely circulatethrough it. Means may should be provided for driving the conveyors* Theupper run is designed to receive the ware 15.

The'tun'nel is formed into a series of compartments or divisions which Ishall designate as A, Awhich is the one at the ware intake end of thekiln, is of such length that when the ware has passed through it, aboutfifteen per slowly and uniformly cent of the moisture has been removed,at which time about forty per cent of the shrinkage takes place. It isvery essential, during this state, that heated air be moved throughtheware 1n the direction indi-cated by the arrows, and that the air atthis point have a great deal more moisture than when first entering thekiln. The moisture at this point is desirable, so as to prevent thesurface of the ware through the division from drying too rapidly with agiven volulne of air, the air being removed through a duct 16 andsupplied through a duct 17.

In order to cause the air to travel slowly A, I have made the sameconsiderably longer than the division F. 'The length of the intermediatedivisions gradually getting shorter toward. the delivery end. -Thelength of this division is ll/gmfeet, while the division F is only 15feet long. It will, therefore, be seen that the velocity of the airthrough the ware in the division A is only about one-third of thevelocity of the air through the ware 1.11 division F. By making eachsuccessive division longer than its preceding one, it will be seen thatthe velocity of the air through the ware is gradually decreased.

In order to get the desired circulation of air through the ware, I havedivided the kiln into a series of upper and lower compartments insomewhat staggered relation to each other. The division F has an inletduct 17 beneath the delivery end of the said division F, and anauxiliarycompartment 18 above the duct 17. This compartment 18 communicates witha compartment 19 above the ware which is substantially 71/2 feet long.The top of the compartment 19 is provided with a horizontal roof 20. Theheight of the roof 20 above the ware is between one and one-half and twotimes the height of the ware. An inclined roof 21 which extendsdownwardly and in the direction of the general movement of the air andis provided B, C, D, E and F, The division Y conveyor.

forv the first part of the compartment 19. The lower edge of the roofmember 21 terminates at a point just above the line of the top of theWare.

This compartment 19 communicates with a compartment 22 beneath the ware,the forward end of which communicates` with the delivery end of thecompartment 23 above the ware` and in division E, which is provided witha horizontal roof 24 and an inclined roof 25. The'forward end of thecompartment 23 communicates with a compart- \ment 26 beneath the ware,which communi- Cates with a compartment 27 above the ware having ahorizontal roof portion 28 and an inclined roof portion 29 of divisionD.

The forward end of the compartment 27 communicates with a compartment 30beneath the ware. The compartments 18, 22 and 26 are formed by simplyplacing transverse partitions 31 between the wallsV `10 and beneath theupper and lower runs of the All of said compartments are provided with ahorizontal floor. Approximately half of the compartment 30 is alsoprovided with a horizontal Hoor. Approximately half of the. compartment30 is provided with an inclined floor 32 which has in longitudinalsection the shape of a hyperbola curve, as clearly illustrated. Thecompartment ."icommunicates with a compartment 33 similar to thecompartments 27.24 and 20 with the exception that the inclined portionis curved and communicating with a compartment 34 beneath` the ware.'This in turn communicates with a compartment 35 above the ware ofdivision B. Approximately half of this compartment is provided with ahorizontal roof 3G,

and the balance with an inclined roof por# tion 37. `The said inclinedportion is curved. A portion of the compartment 34 is provided with acurved bottom 38.

The compartment 35 communicates with the compartment 39 beneath theware, which in turn communicates with the compartment v4() above theware of division A, which is also-provided with a horizontal and curvedroof similar to the compartment of division B, with the exception thatthey are of greater length. The compartment 39 has an inclined bottomportion 41. The compartment 4() communicates with the outlet compartment42 and the outlet duct 1G. The upper portion of the compartment 40 isprovided with a moisture pan 43, which in turn is provided with heatingcoils 44 having a float regulated valve 45 for the purpose ofautomatically supplying moisture through the supplypipe 46.

The practical operation of my drier is substantially -as follows:

Assuming that ware is being delivered to the conveyor 12 and first intodivision A, it will be delivered from the drier kiln at division F. Theconveyor 12 is provided with an extended portion at each end outslde ofthe kiln for the purpose of receiving and delivering the ware. Heatedair may then be delivered to the duct 17 where 1t w1ll pass upwardlythrough the compartment 18 into thel compartment 19, the air bein"propelled by means of an air circulating device such as now in commonuse, the cooled air being exhausted through the duct 16.

When the air has reached the compartment 19, it will be seen that itwill be moved along the top of the roof 20 and the 1nclined portion 21pulled downwardly through the ware most forcibly at the lowest point ofthe roof 21. On account of the short length of division F, it will beseen that air will move at a comparatively high velocity and that eddycurrents will be set upiat the point a somewhat as indicated by thearrows.`

Thus it will be seen that the velocity of the air through the ware iscomparatively high at this point. The air is then pulled through thecompartment 22 into the com` partment 23 of division E. The sameoperation continuing through divisions E and D, eddy currents being setup at the points a, b and c. About eighty-six percent of the shrinkagehas taken place at the time the ware enters division D. y

It will be seen that in these-three divisions, the shape of the roofsand floors need not be very accurately worked out, due to the fact thatthe shrinkage has mostly taken place,` the main object being to get aslarge amount of circulation as possible in these three divisions.

Tn division C I have provided the curved floors 32 and the curvedportion of the iirst half of the roof 33. By forming the floor 32 on thecurve of a hyperbola, I have provided means whereby air will be movedupwardly through the ware as it enters the compartment 33 at a fairlyuniform velocity at all points of the ware. The curved roof portion otthe compartment 33 serves to force the air down through, thecompartment. The same action takes place in the divisions B and A, theonly difference being that the compartments A and B are longer than thecompartment AC and the velocity through the ware is thereby reduced. Itsometimes happens that it is necessary to provide extra moisture as theair enters the compartment 40. This I have accomplished by providingthetank 43, which is supplied with water through the supply pipe 46.

Referring to the drawings illustrating the modified form of my device,itwill be seen that the arrangement is substantially the same with theexception that Iv have pro-l vided beneath the lower compartments ordivisions A, B, C, D and E a passageway for receiving the heated gasesfrom the burnere at atmospheric tem-` colored and to go into chemicalcombinations which are more or less detrimental. By su plying heatthrough radiation, I have viated the above ditliculty.

The passage above referred to consists of an enlarged chamber 50 havinga sheet metal plate 51 above it, which forms a bottom for a portion ofthe compartment 22 and for the compartments 26, 30 and 34. The passage50 is in communication with a transversely arranged passage 52 whichserves as an inlet supply passage. The opposite end of the chamber 50 isprovided with a vertical wall 53, which serves as a support for one endof horizontally arranged pipes 54. The opposite ends of the pipes aremounted in a vertical wall 55. The space between the walls 55 and` 53forms a chamber 56 beneath the compartments 39 and 40. The pipes 54communicate with the exhaust passage -16 and the ends of the pipes thatare mounted in the wall 55 are lower than the ends which are mounted inthe wall 53, so that any con densation of moisture that may be formed 1nthe pipes 54 will run into a trough 57 provided for that purpose.

The practical operation of the modified form of my device is as follows:

Assuming that ware is placed'on the con veyor 12 and is being movedthrough the kiln, either continuously or intermittently, air will bedrawn through the kiln irst through the passage 17 and longitudinallythrough the kiln in the manner described in my preferred form..v andexhausted through the passage 16. This air will be, for illusrtraion, ata temperature of one hundred degrees, and taken directly from theoutside atmosphere. If the kiln is in continuous operation, the warewill be heated to a temperature of probably 24Q-or 250 degrees, and asit advances through the kiln from the left to the right, as illustratedin Figures 5 and 6, the air which passes upwardly through the ware fromthe passage 17" will have a tendency to bring the wareto the temperatureof the incoming air, and the air will thereby he heated, and as itpasses through, the compartment 22 beneath the roof member 21 it will bebrought to a temperature of about degrees, and will from there pass-intothe compartment 23 located above the passage 52. The gases of about 300degrees orv ipso wardly, raising the temperature of the air to about 240degrees, which will then gradually be cooled as 1t is advanced throughthe kiln in about the ratio illustrated in the various compartments.

As the heated gases in the chamber 30 pass backwardly the heat will beradiated through the plate 5l to the compartments above, and when it hasreached the tubular members 54, the temperature will probably be reducedto about 150 degrees. The air which is taken through the inlet 52 may bederived from the chimney of the kiln which contains a large percent ofmoisture, sulphuric acid and other gases which are injurious to metalwhen the temperatures of the gases have been reduced to a point wherecondensation takes place and would be injurious to a thin sheet metalplate. For that reason I have provided the tubes 54 formed of cast ironor any other suitable metal which is not so easily acted upon by theobjectionable gases. After further radiation takes place andthecondensation of the moisture and gases is permitted until substantiallythe total amount of heat has been extracted from the air and also thelatent heatv of the moisture.

It will be seen by this arrangement that I have provided means whereby acomparatively large amount of heat `may be derived or the purpose ofdrying the ware from exhaust gases which would otherwise be wasted.

By providing the chambers 50 and 54 with means for conducting the Wastegases through them, the heat of the same being radiated to thecompartments above, I have provided means whereby the temperature of thewastegases may be lowered at that point,`whereby the latent heat may beutilized for heatmg without being detrimental to the ware. through thekiln as outlined by the arrangement illustrated in Figures l, 2 and 3 ofthe drawings, the condensation would form on the ware and be verydetrimental, due to the fact that instead of drying the ware, it wouldhave a tendency to meisten it, and as far as I am aware, it has neverbeen custom ary to reduce the temperature of the drying air to a pointwhere condensation of the moisture would take place in the kiln to anygreat extent.

Thus it will be seen that the modified form has the advantage ofutilizing a greater percent of the heat from the exhaust gases which areoriginally supplied with moisture for the purpose of drying the ware.

It will further be seen that it also provides means for supplying thedrier with pure air which will keep the ware in clean condition forburning, so a better color may be imparted to the Ware when burned. The

If heated air vwas carried f condensed luid may be drawn from the trough57 and treated as a by-product to l produce sulphur andthe like whichresults in further economy in o eration.

Thus it will be seen t at I have provided a drier ofk comparativelycheap and inex pensive construction, and yet one which is so arrangedand constructed that air may be continuously passed through it and driedat a maximum speed without cracking, breaking or warping the ware.

I claim as my invention:

1.. A drier comprising a tunnel designedv to receive plastic ware, thetunnel being provided with a series of upper compartments, means formoving a current of air through the tunnel from one end to the other,the roof of each of the upper compartments being provided with ahorizontal portion and conveying ware centrally'through the tunnel fromone end to the other, said tunnel being constructed to form a series ofcompartments above and below the ware, means for drawing airlongitudinally through said tunnel, the roof of each ot the compartmentsabove the ware being provided with a horizontal portion and a portionbeing formed on the line of a curve which approaches,

parallelism to the line ot' travel of the ware, a portion of the iloorof each of the lower compartments being formed horizontally, a portionof which isgformed on the line of a curve which approaches parallelismto the line of travel of the ware, said curved portions being designedto cause said air to be forced through the ware in alternate directions.

3. In a drier of the class described comprising a tunnel, means formoving ware through the tunnel from one end t'o the other, means forsupplying heated air to one end of said tunnel and removing it from theopposite end, the air being designed to move in an opposite directionfrom the movement of the ware, an auxiliary moisture supplying tanksituated near the inlet end of the tunnel, and means for supplyingadditional heat to the said auxiliary tank other than that which wouldbe supplied by the heated air of the kiln.

4. In a drier of that class that is adapted to receive and dry plasticware by passing a current of heated air over the ware, an auxiliarymoisture supplying means for the drier situated at a point near to wherethe air is being taken from the drier.

. 5. A drier comprising a tunnel designed to receive a moving row ofplastic ware, the tunnel being divided into a series of above and belowthe ware set in staggered relation to each other and designed to passformed on a the air throu h the ware in reverse directions, meansesigned to moveI the air in an opposite direction romthe travel of. theware, those compartments next to the .inlet end being longerthan thoseat the delivery end of the kiln, for the purposes stated.'

6. A drier comprising substantially a tunnel designed to receive plasticware, the tunnel being provided with a series of upper and lowercompartments, means for moving a current of air through the tunnel fromone end to the other, the roof of each of the upper compartments beingprovided with a horizontal ortion and a portion being line of a curvewhich approaches parallelism to the line of travel of the ware as itnears the final air delivery end and which curved, ceiling forces theair .downwardly through the Ware, the lower compartments being arrangedin staggered relation with the upper compartments and provided withportionsof its ioor formed horizontally and a ortion bein formed on aline of a curve w ichapproac es parallelism to the line of travel of theware as it nears the nal air delivery end, and which curved Hoor forcesthe air upwardly through the ware.

7 A drier comprising substantially a tunnel designed to receive plasticware, the tunnel being provided with a series of upper and lowercompartments, means for moving a current of air thro-ugh the tunnel fromone end to the other, the roor` of each of the upper compartments beingprovided with a horizontal portion and a portion being formed on a lineof a curve which approaches parallelism to the line of travel of theware as it nears the final air delivery end and which curved ceilingforces the'air downwardly through the ware, the lower compartments beingarranged in staggered relation with the upper compartments and providedwith ortions of its floor formed horizontally and a portion being formedon a line of a curve which app-roaches parallelism to the line of travelof the ware as it nears the final air delivery end, and which curvediloor forces the air upwardly through the ware, the curved portions ofthe roof bein opposite the horizontal portions of the oor and the curvedportions of the floor being opposite the horizontal portions of theroof.

8. A drier kiln comprising substantially a tunnel .adapted to receiveware located midway between the top and the bottom,

` means for moving air through the tunnel from one end to the other,said tunnel being provided with a series of upper and lower compartmentsarranged in staggered relation' with each other, said compartments be,-

ingI so shaped and formed that air will be 'moved through the ware atthe dry end of the kiln at a comparatively high velocity and at theopposite end of the kiln at a comparatively low velocity, the saidcompartments being also so arranged that the high velocity will produceeddy currents for the. purpose of producing a large amount ofrecirculation, while the air at the low velocity end of the kiln will becaused. to

move uniformly through the ware.

9. A drier comprising substantially a tunnel adapted to receive warethat is moving through the tunnel from one end to the other, means formoving air through the tunnel in opposite directions to the movement ofthe ware, the walls of the tunnel being so constructed that the'velocity of the air will be lowest at .the point in the kiln where theshrinkage is the greatest.

10. A drier comprising substantially a tunnel designed to receiveplastic ware as it is adapted to be moved from one end of the drier tothe other, means for introducing and moving fresh air through the drierfrom one end to the other, means for introducing a heat bearing mediumat a point between the intake and discharge ends of the drier, the saidmedium being arranged to radiate heat to the drier from its point ofintroduction to its point of discharge.

l1. A drier comprising substantially a tunnel, means for moving plasticwaie longitudinally through the tunnel from one end to the other, meansfor introducing air to the delivery end of said tunnel and taking itfrom the intake end, means for introducing and maintaining a current ofheated air adjacent to oney side of the kiln in such a manner that theheat from the said heated air will be radiated to the tunnel, the pointof introduction being between the inlet and outlet end of said tunnel,and the point of removal being at the inlet end, substantially asdescribed and for the purposes stated.

12. A drier comprising a tunnel having upright side walls parallel witheach other,

means for conveying ware centrally through the kiln from one end to theother so as to form a series of compartments above and below the ware,the compartments above the ware being in staggered relation and incoinmum'cation with those below the ware, and means for drawing airlongitudinally through said compartments so as to cause the air totravel through the ware in alternate reverse directions, thecompartments below the ware being provided with a heat conductive floor,a passage beneath the said floor, the said passage being of a lengthless than the length of the tunnel, and means for introducing heated airto one end of said passage and removing it from the opposite end.

13. A drier comprising substantially a 4tunnel provided with means formoving ware through it from one end to the other, mea-ns for movingfresh air through the Ware in a direct-ion opposite to that in which theware is moved, a passageway located longitudinally adjacent to one sideof the tunnel and adapted t0 receive heated moisture bea-ring gases at apoint inside of the disradiate heat therefrom as it is a vanced 10through said passage, for the purpose of heating the air Within thetunnel, substantially as described and .for the purposes sta-ted.

Des Moines, Iowa, January 12, 1924.

HALVER R. STRAIGHT.

